A radiocarbon dating method which has been used to measure the age of remains having an archeological value means a radiocarbon dating method using a principle of collapsing in-vivo radiocarbon after the death of an organism at a constant ratio.
Three kinds of carbon isotopes such as 12C, 13C, and 14C are mainly present in nature. Here, 12C occupies 98.89% of nature, 13C occupies 1.11% of nature, and a trace of 14C is present in nature. Meanwhile, even though carbon is absorbed into a body of an organism by photosynthesis or breathing, the ratio of 12C, 13C, and 14C keeps unchanged.
However, after the organism is dead, 14C which is instable radiocarbon collapses at a constant rate and thus is changed to 14N. In this case, the organism suffers from a half-life in which an amount of 14 C is reduced half. The age of the organism may be estimated by the fact that the half-life is about 5,730 years.
To measure the age of a sample such as remains by an accelerator mass spectrometry which is one of the radiocarbon dating methods, there is a need to first extract carbon from the sample. This is referred to as a sample pre-treatment process, which generally includes a chemical pre-treatment process, a vacuum combustion process, and a reduction process.
The chemical pre-treatment process is a process of removing impurities from a sample to be analyzed to prevent errors due to pollutants during an analysis process and removes impurities contained in the sample by known cleaning process, chemical treatment process, drying process, and the like to increases analysis reliability.
The vacuum combustion process means a process of combusting a pre-treated sample under the vacuum to obtain carbon dioxide. High-purity oxygen is emitted from a copper oxide (CuO) powder by putting the pre-treated sample, the copper oxide powder, and an Ag wire in a quartz pipe, sealing the quartz pipe using a torch in a vacuum state, putting the sealed quartz pipe in a muffle furnace, and then combusting the quartz pipe at about 850° C. for 2 hours. In this case, the oxygen oxidizes carbon of an original sample at high temperature to generate carbon dioxide. Further, the Ag wire suppresses and precipitates a generation of sulfur which is a by-product of the combustion.
The carbon dioxide which is generated during the foregoing processes passes through a cooling drier in which dry ice and alcohol are mixed several times and then only the carbon dioxide is solidified, separated, and extracted using the liquid nitrogen.
The reduction process means a process of putting mixed gas of carbon dioxide and hydrogen and an iron powder catalyst in a sealed container and then heating them to extract graphite, which is a carbon powder, by a reaction of CO2+2H2→C+2H2O.
The related art manually performs the foregoing graphitization process on each sample. That is, the vacuum combustion process puts the sample, the copper oxide, and the Ag wire in a vacuum pipe, seals the vacuum pipe using the torch in the vacuum state, and then combusts the vacuum pipe and the graphitization process puts the combusted quartz pipe in a flexible bellows of a dry line and breaks the combusted quartz pipe and then sequentially passes the quartz pipe through a liquid nitrogen (LN2)/alcohol trap and an LN2 trap to solidify only pure carbon dioxide (CO2) and collect the solidified carbon dioxide in a carbon dioxide storage tank.
However, the existing method individually performs two steps of the vacuum combustion process and the reduction process on each sample, and as a result, is complicated, has pollution possibility during the processes, and requires much time to perform an operation. Further, when gas in addition to carbon dioxide is mixed due to foreign materials mixed in the sample, it is difficult to confirm and remove the gas. In particular, when gas sulfide is mixed, the reduction reaction itself rarely happens.
To solve the above problem, Patent entitled “Graphitization Apparatus And Graphitization Method Using The Same” (Korean Patent No. 10-0998227) registered on Nov. 29, 2010 is issued to the present applicant.
According to the above Patent, as illustrated in FIG. 1, the graphitization apparatus includes an elemental analyzer 10 configured to include a sample combustor 11 which combusts a sample and a combustion gas separator 12 which primarily removes impurities included in combustion gas generated from the sample combustor 11 using a gas chromatographic method, a carbon dioxide collector 30 configured to choose and collect only carbon dioxide from the combustion gas passing through the elemental analyzer 10, a reduction reactor 40 configured to reduce the carbon dioxide collected through the carbon dioxide collector 30 to graphite, and a controller 50 configured to control operations of the elemental analyzer 10, the carbon dioxide collector 30, and the reduction reactor 40.
By the above configuration, it is possible to maximally suppress mixing possibility of impurity by primarily removing impurities included in combustion gas of an organic matter using the gas chromatographic function of the elemental analyzer (EA) and then collecting carbon dioxide, to suppress an isotope fractionation effect by remarkably promoting a ratio at which the carbon dioxide is graphitized by optimizing a reaction condition of the graphitization process, to remarkably reduce time required for reaction by optimizing a ration of a reaction container, and to obtain sufficient graphite required for carbon dating only by using a minimum amount of sample.